Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by widespread immunologic abnormalities and multi-organ involvement. However no useful markers exist to help determine, either at the time of diagnosis or during the course of disease, which patients will develop life-threatening events. Likewise there are no reliable markers to predict disease flares or response to treatment. Juvenile SLE can be distinguished clinically from adult onset SLE. Thus there may be distinct markers of disease activity in children and adults. The purpose of these studies is to identify molecular markers of SLE and predictors of disease activity in children with SLE. These markers will aid in the diagnosis and treatment of this disease.